At first glance, Gaby Mortimer could almost be a character from Having It and Eating It, the mum-lit novel with which Sabine Durrant made her name. A morning television presenter, she's the sort of woman who has it all: handsome husband, gorgeous south London house, cute kid, impressive job. But, out jogging early one morning – not that Gaby would call it a jog; "jogging's dated… it's a run" – she discovers a dead body, and her perfect life begins to unravel.

"They say," states the cover line on Under Your Skin, "the innocent have nothing to fear", but why, ask the police, didn't Gaby tell them that she touched the body? Isn't it strange, they say, how similar the dead woman, Ania, looks to Gaby? Why did Ania have a collection of cuttings about Gaby in her flat? Why does the evidence point towards a link between the two women, and why does Gaby keep denying it? All of a sudden, Gaby finds herself arrested, spending the night in a prison cell, vehemently protesting her innocence. Her legendary charm isn't working on Detective Inspector Perivale. And she becomes the story.

Durrant has peopled her first venture into thrillers with a host of suspicious characters: Philip, the husband, on a business trip abroad and strangely reluctant to answer Gaby's increasingly frantic phone calls. Marta, the nanny, whom Gaby catches looking at her with contempt, and who has an almost unhealthy attachment to her daughter. Gaby's mysterious stalker, who has been watching her for weeks.

And then there's Gaby herself, Durrant's narrator. From the outside, she might appear to have been living a charmed life, but Durrant shows us almost from the start what an act this is. Brittle, miserable, Gaby gets every social interaction subtly, disastrously, wrong, misinterprets jokes, plays it for laughs in the police station.

"I suspect he is joking, but I feel a trickle of anxiety," she worries. And "I'm expecting her to smile too, but she doesn't". Later: "There is something about the way I say 'sexy' that makes me want to hide under the table." She might visit cafes where "it's so trendy… the coffee is 'artisan-roasted'", but she doesn't sit easily in her life; it's almost as if it's too hard a performance for her to pull off. "My breath is ragged. I can feel it, hot, in my chest. It's all wrong; I'm not doing it right. I'm hopeless; I'm a person who can't even run properly," she says.

Under Your Skin rapidly unravels into a maelstrom of tension and paranoia, as Durrant draws a disturbing picture of how easy it is for even the most perfect life to implode. All too quickly, there is nowhere for Gaby to turn, and she waits alone in the dark in her Wandsworth house.

It's hard to know whether to be enraged or delighted by the unexpected denouement with which Durrant wraps up her story, but if the mark of a good thriller is the compulsion to reread it immediately on finishing, to see if the clues can be spotted second time round, then Under Your Skin has it, in spades.